Homophobia is a pervasive social disease, appears to be common and socially acceptable in our culture, and leads to hate crimes and psychological distress among the victims. The determinants of homophobia are not fully understood. One proposed determinant, that homophobia is a negative affective response as a result of an initial defensive reaction to uncertainty about one's own sexual orientation, has eluded empirical researchers. A major reason for this elusiveness is that such an unconscious process is not easily observable by explicit means. The current application seeks to measure this affectively negative reaction to homosexuals using a methodology focused on an implicit measure, specifically startle eye blink. The first study (Specific aim 1) will assess gender differences in response to homosexual stimuli. The second study will assess shorter-lead versus longer-lead differences in this effect (Specific aim 2), while the third will extend these findings by cross-validating the specificity of this implicit measure of affect by assessing homosexual responses (Specific aim 3). The successful completion of these aims will elucidate this potentially very dangerous aspect of human nature by allowing researchers to physiologically tap this unconscious phenomenon. Once startle eye blink is established as a valid measure of the affective component of homophobia, this methodology will be useful in measuring potential mediators and moderators of this effect, with the ultimate goal of developing an early intervention, before these emotions become ingrained in the individual.